quiddity
Responses from quiddity
| Direct drive/rim drive/idler drive vs. belt drive? Axelwahl, On your first point: That one's easy. I take it as a truth universally acknowledged that if the motor were not running, frictional forces (of whatever source) would cause the system to slow down and in doing so it would lose kinetic ener... | |
| Direct drive/rim drive/idler drive vs. belt drive? And to take that theme and refer back to the OPs question, I might ask: how much of the total inertia of the system should the platter represent? What influence does splitting some or most of the inertia away from the platter have on the perceived... | |
| Direct drive/rim drive/idler drive vs. belt drive? From the Websters dictionary 1905 edition: "A barbarous term used in school philosopy for essence" - gotta love a dictionary with that degree of vitriol.My intended career was as an academic in philosophy. My chosen field was logic and the structu... | |
| Direct drive/rim drive/idler drive vs. belt drive? Johnny BYou don't seem to understand the function of a low pass filter. It is not possible for the belt drive flex per se to affect anything by more than a few parts per million for the reasons given. A change in belt tension will however create b... | |
| Direct drive/rim drive/idler drive vs. belt drive? I was thinking about the SL1200 series - the SP10s used push pull pairs on a dual rail power supply. Since there is no coupling capacitor it can't be the problem but it is still the case that the amplifier will be sensitive to the quality of its p... | |
| Direct drive/rim drive/idler drive vs. belt drive? Albert that's not strange at all when you look at the way Technics implemented their servo drives. They drive the motor coils with single ended amplifiers using capacitive coupling to block the inevitable DC offset. Any such amplifier is very sens... | |
| Direct drive/rim drive/idler drive vs. belt drive? Johnny The net effect of the belt stretch is that it causes creep over the drive pulley, so we are talking about the same thing.The direct effect which you postulate is reduced by the second order low pass filter formed by the belt / platter combi... | |
| Direct drive/rim drive/idler drive vs. belt drive? Albert I measured those results in my lab on a Garrard motor I know is in good working order. I have also measured several other motors used in idlers and found very similar results. Since the results accord with the theoretical results expected f... | |
| Direct drive/rim drive/idler drive vs. belt drive? OopsI looked at the wrong motor on the Hurst table, the actual motor used by VPI is the lower torque model so the figures are 16mNm at the shaft and 290mNm at the platter respectively. This would seem to favour the Garrard but only if you find a 1... | |
| Direct drive/rim drive/idler drive vs. belt drive? The first thing to deal with is the torque issue. The thing about high torque idler motors versus low torque belt motors is largely a furphy.The output torque at the shaft of the Garrard motor is a little under 10 mNm. The output torque at the sha... | |
| New Aluminum Platter from VPI "Another possibility is that my two-phase Kelly drive controller is doing a better job" - it had better be!Try tweaking the third harmonic control whilst running the platter, you should be able to find a minimum in the cogging torque transmitted.... | |
| Why is the price of new tonearms so high Ahh, so all along you were putting us off the scent in our quest for understanding. Silly me, I thought it was because you had a completely inadequate grasp of the fundamental physics underlying the phenomena we were discussing.Thank you so much f... | |
| Why is the price of new tonearms so high Axelwahl The only advantage I can quantify for spring applied VTF is one that seems to have have been ignored in this thread, namely immunity to movement in response to externally applied acceleration (read noise). As I see it, get rid of the nois... | |
| Why is the price of new tonearms so high Axelwahl your last point is where things get interesting.Like everything else it is a matter of compromise. As you have noted, a low inertia arm reduces the maximal VTF variation. The compliance required to keep the resonant frequency in the right... | |
| Why is the price of new tonearms so high Dertonarm That is completely wrong (again). The resonant frequency changes because the moment of inertia changes. The effective mass is simply the moment of inertia divided by the square of the effective length. The total mass is irrelevant to the... |